include <stdio.h>

include <stdlib.h>

include <string.h>

include

include

using namespace std;

define mod 1000000007

long long arr[200005];

void init() {

arr[0] = 1;
for (int i = 1; i < 200001; ++i) {
    arr[i] = arr[i - 1] * i % mod;
}

}

long long func(long long a, long long b, long long c) {

long long ret = 1;
while (b) {
    if (b & 1) {
        ret = ret * a % c;
    }
    a = a * a % c;
    b = b >> 1;
}
return ret;

}

long long work(long long a, long long b) {

return arr[a] * func(arr[a - b] * arr[b] % mod, mod - 2, mod) % mod;

}

int main() {

init();
int n, m;
while (scanf("%d%d", &n, &m) != EOF) {
    printf("%lld\n", work(n - 2 + m - 2, n - 2));
}
return 0;

}